I think I love you, David Cassiday

David Cassidy, the actor, singer and teen heartthrob best known as the band member with the green eyes and the feathered haircut on “The Partridge Family,” the 1970s television show about a family band, died on Tuesday in a hospital in Fort Lauderdale, Fla. He was 67.

His publicist, Jo-Ann Geffen, said the cause was liver failure. Mr. Cassidy, who lived in Fort Lauderdale, had recently been admitted to the hospital in critical condition.

Mr. Cassidy rose to fame on “The Partridge Family” playing Keith Partridge, the eldest of five children in a family that forms a band and goes on tour in a multicolored bus. His character, a high school student, was swooned over by young women as he learned to navigate his newfound fame.

It was 1970, with the turbulent late 1960s of the Vietnam War, race riots, psychedelia, Woodstock and Altamont barely past, when Mr. Cassidy got the lead role on the show. “The Partridge Family” was produced by Screen Gems, which had also been the company behind “The Monkees,” another sitcom about a pop band, which had its own heartthrob in Davy Jones.

Mr. Cassidy had a face youthful enough to portray a teenager, a shy smile and friendly eyes, and he could sing well enough to portray Keith Partridge without having to lip-sync someone else’s voice.

Even in the FM-radio heyday of Black Sabbath, the Allman Brothers and Emerson, Lake & Palmer, there was a place for a well-groomed, unthreatening young pop singer. Mr. Cassidy became one of the teen idols of the early 1970s, arriving between Bobby Sherman and Donny Osmond and decades before Justin Timberlake or Charlie Puth. He was marketed through Top 40 radio and fan magazines as a wholesome fantasy figure for girls.

Soon after “The Partridge Family” began, he had a No. 1 hit, “I Think I Love You,” credited (as many of his hits were) to the Partridge Family.

“The Partridge Family” lasted from 1970 to 1974, a respectable run for a show featuring a teenage idol. In 1972, in what he recalled as a career peak, Mr. Cassidy headlined Madison Square Garden, wearing the kind of white jumpsuit Elvis Presley also favored in the 1970s. By then, he was already weary of incessant career demands and squealing mobs.

“Oh, they’re cute — they get flustered and I get flustered, and it’s all kind of fun,” Mr. Cassidy said of his fans in 1972, when he was 21. “But it’s no fun when they rip your clothes and take rooms next door in hotels and keep pounding on the door and slipping notes under it.”

In an attempt to spice up his squeaky-clean image, Mr. Cassidy posed nude in a photo shoot for the cover of Rolling Stone in 1972. In the article, he said he was already dreaming about the end of his acting career.

“I’ll feel really good when it’s over,” he said. “I have an image of myself in five years. I’m living on an island. The sky is blue, the sun is shining. And I’m smiling, I’m healthy, I’m a family man.”

Mr. Cassidy was nominated for a Grammy Award for best new artist in 1970, and his 1972 solo album, “Cherish,” went gold. The Partridge Family had six albums achieve that certification from 1970 to 1972.

According to an online biography of the Partridge Family by Ed Hogan, Mr. Cassidy and his co-star and real-life stepmother, the Academy Award-winning actress Shirley Jones, were the only cast members on the television show heard on the group’s records — Mr. Cassidy as a lead vocalist and Ms. Jones on background vocals.

He was among the early pop talents to come to notice through television. Reviewing the 1972 concert at Madison Square Garden, held on a Saturday afternoon, Don Heckman wrote in The New York Times that the show “was less a musical event than a love feast, less a concert than a symbolic announcement of what pop music might become.”

“The focus of it all,” he added, “was David Cassidy, singer and star of television’s ‘The Partridge Family’ and the current idol of almost every 13‐year‐old girl in America.”

In later years, he wrote books about the toll that stardom had taken on him, and about his struggles with substance abuse. He revealed this year that he had dementia.

Mr. Cassidy was born on April 12, 1950, in New York City to the actors Jack Cassidy and Evelyn Ward. (Jack Cassidy, who later married Shirley Jones, died at 49 in 1976 in a fire at his Los Angeles apartment. Ms. Ward died at 89 in 2013.)

He grew up in West Orange, N.J., and moved to California when he was still a boy. He struggled in school but began taking small parts in plays and on television, eventually leading to his big break on “The Partridge Family.”

He was later seen on several other television series. A 1978 appearance on “Police Story” earned him an Emmy Award nomination, and he had his own short-lived crime show, “David Cassidy — Man Undercover,” in the 1978-79 season. In 2001 he was fired by Donald J. Trump on “The Celebrity Apprentice.”

Mr. Cassidy was married and divorced three times. He is survived by his son, Beau, a musician; his daughter, Katie, an actress; Ms. Jones, his stepmother; and three half brothers: Shaun Patrick and Ryan.